Data receiving circuit

ABSTRACT

A data receiving circuit is provided. The data receiving circuit includes a first transistor, a second transistor, a third transistor, and a latch circuit. The first transistor has a gate configured to receive an input signal. The latch circuit is configured to output an output signal in response to the input signal. The second transistor has a gate configured to receive a first signal and a drain connected to the latch circuit. The third transistor has a gate configured to receive the first signal and a drain connected to the latch circuit. The second transistor and the third transistor are configured to provide a current to the latch circuit in response to the first signal.

TECHNICAL FIELD

The present disclosure relates to a data receiving circuit and a method of operating the same, and more particularly, to a data receiving circuit having a sense amplifier.

DISCUSSION OF THE BACKGROUND

In memory devices, input receivers are widely used to receive input signals. However, as requirements for the operation speed of memory devices are getting higher and higher, input receivers may not be able to keep up, resulting in a small margin to correctly determine input data. In the event that input data is incorrectly interpreted, memory devices may crash or operate abnormally.

This Discussion of the Background section is provided for background information only. The statements in this Discussion of the Background are not an admission that the subject matter disclosed herein constitutes prior art with respect to the present disclosure, and no part of this Discussion of the Background may be used as an admission that any part of this application constitutes prior art with respect to the present disclosure.

SUMMARY

One aspect of the present disclosure provides a data receiving circuit. The data receiving circuit includes a data input circuit, a latch circuit, and a current source. The data input circuit is configured to receive an input signal. The latch circuit is configured to output an output signal in response to the input signal. The current source is configured to provide a current to the latch circuit. The current source is different from the data input circuit

Another aspect of the present disclosure provides a data receiving circuit. The data receiving circuit includes a first transistor, a second transistor, a third transistor, and a latch circuit. The first transistor has a gate configured to receive an input signal. The latch circuit is configured to output an output signal in response to the input signal. The second transistor has a gate configured to receive a first signal and a drain connected to the latch circuit. The third transistor has a gate configured to receive the first signal and a drain connected to the latch circuit. The second transistor and the third transistor are configured to provide a current to the latch circuit in response to the first signal.

The foregoing has outlined rather broadly the features and technical advantages of the present disclosure so that the detailed description of the disclosure that follows may be better understood. Additional features and advantages of the disclosure will be described hereinafter, and form the subject of the claims of the disclosure. It should be appreciated by those skilled in the art that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures or processes for carrying out the same purposes of the present disclosure. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the disclosure as set forth in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present disclosure may be derived by referring to the detailed description and claims when considered in connection with the Figures, where like reference numbers refer to similar elements throughout the Figures, and:

FIG. 1A is a schematic diagram illustrating a data receiving circuit, in accordance with some embodiments of the present disclosure.

FIG. 1B illustrates timing diagrams of waveforms at different nodes of the data receiving circuit as shown in FIG. 1A, in accordance with some embodiments of the present disclosure.

FIG. 1C illustrates an equivalent circuit of the data receiving circuit as shown in FIG. 1A, in accordance with some embodiments of the present disclosure.

FIG. 1D illustrates an equivalent circuit of the data receiving circuit as shown in FIG. 1A, in accordance with some embodiments of the present disclosure.

FIG. 2A is a schematic diagram illustrating a data receiving circuit, in accordance with some embodiments of the present disclosure.

FIG. 2B illustrates timing diagrams of waveforms at different nodes of the data receiving circuit as shown in FIG. 2A, in accordance with some embodiments of the present disclosure.

FIG. 2C illustrates timing diagrams of waveforms at different nodes of the data receiving circuit as shown in FIG. 2A, in accordance with some embodiments of the present disclosure.

FIG. 2D illustrates an equivalent circuit of the data receiving circuit as shown in FIG. 2A, in accordance with some embodiments of the present disclosure.

DETAILED DESCRIPTION

Embodiments, or examples, of the disclosure illustrated in the drawings are now described using specific language. It shall be understood that no limitation of the scope of the disclosure is hereby intended. Any alteration or modification of the described embodiments, and any further applications of principles described in this document, are to be considered as normally occurring to one of ordinary skill in the art to which the disclosure relates. Reference numerals may be repeated throughout the embodiments, but this does not necessarily mean that feature(s) of one embodiment apply to another embodiment, even if they share the same reference numeral.

It shall be understood that, although the terms first, second, third, etc., may be used herein to describe various elements, components, regions, layers or sections, these elements, components, regions, layers or sections are not limited by these terms. Rather, these terms are merely used to distinguish one element, component, region, layer or section from another region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present inventive concept.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limited to the present inventive concept. As used herein, the singular forms “a,” “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It shall be further understood that the terms “comprises” and “comprising,” when used in this specification, point out the presence of stated features, integers, steps, operations, elements, or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or groups thereof.

FIG. 1A is a schematic diagram illustrating a data receiving circuit 100 (or a data receiver) in accordance with some embodiments of the present disclosure. The data receiving circuit 100 includes an input circuit 110, a latch circuit 120, and an equalizer 130. In some embodiments, the data receiving circuit 100 may be or may include a sense amplifier. In some embodiments, the input circuit 110 and the latch circuit 120 may be collectively referred to as a sense amplifier.

The input circuit 110 includes transistors T11, T12, and T13. In some embodiments, the transistors T11, T12, and T13 are P-type metal-oxide-semiconductor (PMOS) transistors. A source of the transistor T11 is connected to receive a supply voltage Vdd. A gate of the transistor T11 is connected to receive a clock signal V1. A drain of the transistor T11 is connected to a source of the transistor T12 and a source of the transistor T13. A gate of the transistor T12 is connected to receive a reference signal V2. A drain of the transistor T12 is connected to the latch circuit 120 (e.g., to a source of the transistor T21). A gate of the transistor T13 is connected to receive an input signal Vin. A drain of the transistor T13 is connected to the latch circuit 120 (e.g., to a source of the transistor T23). In some embodiments, the reference signal V2 has a voltage level in a range from about 0.1 Vdd to about 0.42 Vdd. In other embodiments, the reference signal V2 may have other voltage levels depending on design requirements. In some embodiments, the input signal Vin has a voltage level in a range from about -0.2 V to about Vdd+0.2 V. In other embodiments, the input signal Vin may have other voltage levels depending on design requirements.

The latch circuit 120 may include two inverters in which an output of one inverter is connected to an input of the other inverter. As shown in FIG. 1A, the latch circuit 120 includes transistors T21, T22, T23, and T24. The transistors T21 and T22 define an inverter while the transistors T23 and 24 define the other inverter. The transistors T21 and T23 are PMOS transistors and the transistors T22 and T24 are N-type metal-oxide-semiconductor (NMOS) transistors.

A source of the transistor T21 is connected to the drain of the transistor T12. A gate of the transistor T21 is connected to a gate of the transistor T22, a drain of the transistor T23, and a drain of the transistor T24. A drain of the transistor T21 is connected to a drain of the transistor T22. A source of the transistor T22 is connected to a common voltage (e.g., ground). The drain of the transistor T21 and the drain of the transistor T22 may function as an output Vout 1 of the data receiving circuit 100.

A source of the transistor T23 is connected to the drain of the transistor T13. A drain of the transistor T23 is connected to a drain of the transistor T24. A source of the transistor T24 is connected to the common voltage (e.g., ground). The drain of the transistor T23 and the drain of the transistor T24 may function as an output Vout 2 of the data receiving circuit 100.

The equalizer 130 includes transistors T31, T32, T33, T34, and T35. In some embodiments, the transistors T31, T32, T33, T34, and T35 are NMOS transistors. Gates of the transistors T31, T32, T33, T34, and T35 are connected to each other to receive an equalizing signal Veq. A source of the transistor T31 is connected to the common voltage (e.g., ground). A source of the transistor T33 is connected to the common voltage (e.g., ground). A source of the transistor T34 is connected to the common voltage (e.g., ground). A source of the transistor T35 is connected to the common voltage (e.g., ground). The transistor T32 is connected between the transistors T31 and T33.

FIG. 1B illustrates timing diagrams of waveforms at different nodes of the data receiving circuit 100 as shown in FIG. 1A, in accordance with some embodiments of the present disclosure.

In some embodiments, prior to the time T1, the data receiving circuit 100 is configured to operate at an equalizing stage. In this stage, the equalizer 130 is enabled. The equalizing signal Veq with a high logic level (e.g., logical value “1”) is inputted to the gates of the transistors T31, T32, T33, T34, and T35 to turn on those transistors. Thus, the voltages Vcom 1 at the drain of the transistor T12, Vcom 2 at the drain of the transistor T13, Vout 1, and Vout 2 would be pulled down to the common voltage (e.g., ground) as shown in FIG. 1C, which illustrates an equivalent circuit of the data receiving circuit 100 operating in the equalizing stage.

After the time T1, the equalizing stage is completed, and thus the equalizing signal Veq with a low logic level (e.g., logical value “0”) is inputted to the gates of the transistors T31, T32, T33, T34, and T35 to turn off those transistors. The equalizer 130 is turned off. FIG. 1D illustrates an equivalent circuit of the data receiving circuit 100 operating in this stage, in accordance with some embodiments of the present disclosure.

At the time T1, an input signal Vin having a high logic level (e.g., logical value “1”) is inputted to the gate of the transistor T13. The voltage Vtop at the drain of the transistor T11 (or at the source of the transistor T12 or T13) starts rising. For example, the voltage Vtop is pulled up. The voltage Vcom 1 at the drain of the transistor T12 (or at the source of the transistor T21) starts rising as well. For example, the voltage Vcom 1 is pulled up. The voltage Vcom 2 at the drain of the transistor T13 (or at the source of the transistor T23) starts rising as well. For example, the voltage Vcom 2 is pulled up.

Since the voltage (e.g., the input signal Vin) at the gate of the transistor T13 is higher than the voltage (e.g., the reference signal V2) at the gate of the transistor T12, a current I11 flowing through the transistor T12 is larger than a current I12 flowing through the transistor T13. After a sufficient period of time, the transistor T21 is fully turned on. Since the voltage Vout 2 at the gates of the transistors T21 and T22 has been pulled down to the common voltage (e.g., ground) during the equalizing stage, the transistors T21 and T24 are fully turned on and the transistors T22 and T23 are fully turned off. Therefore, the voltage Vout 1 at the drains of the transistors T21 and T22 (or at the gates of the transistors T23 and T24) starts rising at the time T2. For example, the voltage Vout 1 is pulled up at the time T2.

In some embodiments, at the time T2, the data receiving circuit 100 is configured to operate at a data development stage. At the time T3, the voltage Vout 1 at the drains of the transistors T21 and T22 (or at the gates of the transistors T23 and T24) has been completely pulled up to the high logic level (e.g., logical value “1”). In some embodiments, during the time T3 and the time T4, the data receiving circuit 100 is configured to operate at a data latch stage.

After a period for data input (e.g., from the time T1 to the time T4) has been completed, the data receiving circuit 100 is configured to operate at an equalizing stage again at the time period T4.

When operating during the period for data input (e.g., from the time T1 to the time T4), the data receiving circuit 100 is configured to output the voltage Vout 1 having a high logic level (e.g., logical value “1”) if the voltage of the input signal Vin is higher than the voltage of the reference signal V2; and the data receiving circuit 100 is configured to output the voltage Vout 1 having a low logic level (e.g., logical value “0”) if the voltage of the input signal Vin is lower than the voltage of the reference signal V2. However, due to the parasitic elements (e.g., resistance, inductance and/or capacitance) existing at the drains of the transistors T12 and T13, the current I11 and the current I12 have to charge (or discharge) said parasitic elements to pull up (or pull down) the voltages Vcom 1 and Vcom 2.

As shown in FIGS. 1A and 1D, the current I11 and the current I12 are determined by the transistors T12 and T13, respectively. For example, the current I11 (or the current I12) can be determined by a voltage difference between the source and the gate (e.g., Vsg) of the transistor T12 (or the transistor T13). However, due to relatively high voltages V2 (e.g., about 0.1 Vdd to about 0.42 Vdd) and Vin (about Vdd+0.2 V) at the gates of the transistors T12 and T13, the current I11 and the current I12 would be reduced, which would render a relatively longer rising time (or falling time) of the voltage Vout 1. For example, as shown in FIG. 1B, the voltage Vout 1 rises slowly compared with the input signal Vin. This situation becomes serious when the operation speed of the data receiving circuit 100 increases. In some cases, the voltage Vout 1 may not correctly reflect the input signal Vin, causing the data receiving circuit 100 to be abnormal.

FIG. 2A is a schematic diagram illustrating a data receiving circuit 200 (or a data receiver), in accordance with some embodiments of the present disclosure. The data receiving circuit 200 includes an input circuit 410, a latch circuit 420, an equalizer 430, a current source (or a current sink) 440, and a pulse generator 450. In some embodiments, the data receiving circuit 200 may be or may include a sense amplifier.

The input circuit 410 includes transistors T41, T42, and T43. In some embodiments, the transistors T41, T42, and T43 are P-type metal-oxide-semiconductor (PMOS) transistors. A source of the transistor T41 is connected to receive a supply voltage Vdd. A gate of the transistor T41 is connected to receive a signal V3 from the pulse generator 450. A drain of the transistor T41 is connected to a source of the transistor T42 and a source of the transistor T43. A gate of the transistor T42 is connected to receive a reference signal V5. A drain of the transistor T42 is connected to the latch circuit 420 (e.g., to a drain of a transistor T51, a drain of the transistor T52, a gate of the transistor T53, and a gate of the transistor T54). The drain of the transistor T42 is also connected to the equalizer 430. A gate of the transistor T43 is connected to receive an input signal Vin 1. A drain of the transistor T43 is connected to the latch circuit 420 (e.g., to a drain of a transistor T53, a drain of the transistor T54, a gate of the transistor T51, and a gate of the transistor T52). The drain of the transistor T43 is also connected to the equalizer 430.

In some embodiments, the reference signal V5 has a voltage level in a range from about 0.1 Vdd to about 0.42 Vdd. In other embodiments, the reference signal V5 may have other voltage levels depending on design requirements. In some embodiments, the input signal Vin 1 has a voltage level in a range from about -0.2 V to about Vdd+0.2V. In other embodiments, the input signal Vin 1 may have other voltage levels depending on design requirements.

The latch circuit 420 may include two inverters (e.g., the inverters IN1 and IN2 as shown in FIG. 2D) in which an output of one inverter is connected to an input of the other inverter. As shown in FIG. 2A, the latch circuit 420 includes transistors T51, T52, T53, and T54. The transistors T51 and T52 define an inverter while the transistors T53 and 54 define the other inverter. The transistors T51 and T53 are PMOS transistors and the transistors T52 and T54 are N-type metal-oxide-semiconductor (NMOS) transistors.

A source of the transistor T51 is connected to the current source 440 (e.g., to a drain of a transistor T71). A gate of the transistor T51 is connected to a gate of the transistor T52, a drain of the transistor T53, and a drain of the transistor T54. A drain of the transistor T51 is connected to a drain of the transistor T52. A source of the transistor T52 is connected to a common voltage (e.g., ground). The drain of the transistor T51 and the drain of the transistor T52 may function as an output Vout 3 of the data receiving circuit 200.

A source of the transistor T53 is connected to the current source 440 (e.g., to a drain of a transistor T72). A drain of the transistor T53 is connected to a drain of the transistor T54. A source of the transistor T54 is connected to the common voltage (e.g., ground). The drain of the transistor T53 and the drain of the transistor T54 may function as an output Vout4 of the data receiving circuit 200.

The equalizer 430 includes transistors T61, T62, T63, T64, and T65. In some embodiments, the transistors T61, T62, T63, T64, and T65 are NMOS transistors. Gates of the transistors T61, T62, T63, T64, and T65 are connected to each other to receive an equalizing signal Veq 1 . A source of the transistor T61 is connected to the common voltage (e.g., ground). A source of the transistor T63 is connected to the common voltage (e.g., ground). A source of the transistor T64 is connected to the common voltage (e.g., ground). A source of the transistor T65 is connected to the common voltage (e.g., ground). The transistor T62 is connected between the transistors T61 and T63.

The current source 440 includes transistors T71 and T72. In some embodiments, the transistors T71 and T72 are PMOS transistors. A source of the transistor T71 is connected to receive a supply voltage Vdd. A gate of the transistor T71 is connected to receive a signal V4. A drain of the transistor T71 is connected to the latch circuit 420. A source of the transistor T72 is connected to receive a supply voltage Vdd. A gate of the transistor T72 is connected to receive a signal V4. A drain of the transistor T72 is connected to the latch circuit 420.

The pulse generator 450 may include an inverter G1, a delay circuit (or a buffer) G2, and an NAND gate G3. FIG. 2B illustrates timing diagrams of waveforms at different nodes of the pulse generator 450, in accordance with some embodiments of the present disclosure.

In operation, the pulse generator 450 is configured to receive an input (e.g., the signal V4) having a first logical value with a period P1 and to generate an output (e.g., the signal V3) having a second logical value with a period P2. In some embodiments, the first logical value is different from the second logical value. For example, as shown in FIG. 2B, the first logical value is 1 and the second logical value is 0. In some embodiments, the period P2 is less than the period P1. For example, P2 is equal to n×P1, where 0 < n < 1. In some embodiments, n is about ⅓.

In some embodiments, n can be determined by the delay time of the delay circuit G2. As shown in FIG. 2B, at the time TG1, the signal V4 having a logical value “1” is inputted to the pulse generator 450. The inverter G1 is configured to generate an output signal A having a logical value “0.” The delay circuit G2 is configured to generate an output signal B having a logical value “1” at the time TG2. The difference between the time TG2 and the time TG1 is the delay time of the delay circuit G2. At the time TG3, the signal V4 having a logical value “0” is inputted to the pulse generator 450. The inverter G1 is configured to generate an output signal A having a logical value “1.” The delay circuit G2 is configured to generate an output signal B having a logical value “0” at the time TG4. During the time TG3 and the time TG4, both the inverter G1 and the delay circuit G2 are configured to generate signals having a logical value “1,” and thus the NAND gate G3 is configured to generate the signal V3 having a logical “0.” In some embodiments, the difference between the time TG4 and the time TG3 is the period P2 of the pulse signal (e.g., the signal V3) generated by the pulse generator 450. In some embodiments, the difference between the time TG4 and the time TG3 is the delay time of the delay circuit G2.

FIG. 2C illustrates timing diagrams of waveforms at different nodes of the data receiving circuit 200 as shown in FIG. 2A, in accordance with some embodiments of the present disclosure.

In some embodiments, prior to the time T5, the data receiving circuit 200 is configured to operate at an equalizing stage. In this stage, the equalizer 430 is enabled. The equalizing signal Veq 1 with a high logic level (e.g., logical value “1”) is inputted to the gates of the transistors T61, T62, T63, T64, and T65 to turn on those transistors. Thus, the voltages Vcom 3, Vcom 4, Vout 3, and Vout4 would be pulled down to the common voltage (e.g., ground).

After the time T5, the equalizing stage is completed, and thus the equalizing signal Veq 1 with a low logic level (e.g., logical value “0”) is inputted to the gates of the transistors T61, T62, T63, T64, and T65 to turn off those transistors. The equalizer 430 is turned off. FIG. 2D illustrates an equivalent circuit of the data receiving circuit 100 operating in this stage, in accordance with some embodiments of the present disclosure.

At the time T5, an input signal Vin 1 having a high logic level (e.g., logical value “1”) is inputted to the gate of the transistor T43. Meanwhile, the signals V3 and V4 having a logical value “0” (e.g., during the time TG3 and the time TG4 as shown in FIG. 2B) are inputted to the gates of the transistors T41, T71, and T72 to turn on the transistors T41, T71, and T72. The voltage Vtop 1 at the drain of the transistor T41 (or at the source of the transistor T42 or T43) starts rising. For example, the voltage Vtop 1 is pulled up. The voltage Vcom 3 at the drain of the transistor T71 starts rising as well. For example, the voltage Vcom 3 is pulled up. The voltage Vcom 4 at the drain of the transistor T72 starts rising as well. For example, the voltage Vcom 4 is pulled up.

Since the voltage (e.g., the input signal Vin 1) at the gate of the transistor T43 is higher than the voltage (e.g., the reference signal V5) at the gate of the transistor T42, the voltage Vout 3 at the drains of the transistors T51 and T52 (or at the gates of the transistors T53 and T54) starts rising as well. For example, the voltage Vout 3 is pulled up. After a period for data input (e.g., from the time T5 to the time T6) has been completed, the data receiving circuit 200 is configured to operate at an equalizing stage again at the time period T6.

When operating during the period for data input (e.g., from the time T5 to the time T6), the data receiving circuit 200 is configured to output the voltage Vout 3 having a high logic level (e.g., logical value “1”) if the voltage of the input signal Vin 1 is higher than the voltage of the reference signal V5; and the data receiving circuit 200 is configured to output the voltage Vout 3 having a low logic level (e.g., logical value “0”) if the voltage of the input signal Vin 1 is lower than the voltage of the reference signal V5. After the input signal Vin 1 has been inputted to the transistor T43 and before the data operation has been completed by the latch circuit 420 (e.g., after the time TG4 as shown in FIG. 2B), the pulse generator 450 is configured to generate the signal V3 having a logical value “1” to turn off the transistor T41, so as to prevent the circuit from being damaged due to a short circuit between Vdd and ground.

In accordance with some embodiments, as shown in FIGS. 2A-2D, during the period for data input, the gates of the transistors T41, T71, and T72 are inputted with signals having a logical value “0.” In other words, during the period for data input, the gates of the transistors T41, T71, and T72 are connected to ground. Therefore, a voltage difference between the source and the gate (e.g., Vsg) of the transistor T71 (or the transistor T72) is higher than a voltage difference between the source and the gate (e.g., Vsg) of the transistor T12 (or the transistor T13) as shown in FIG. 1A, which renders the current I13 and the current I14 generated by the transistors T71 and T72 larger than the current I11 and the current I12 generated by the transistors T12 and T13. Compared with the data receiving circuit 100 as shown in FIG. 1A, the data receiving circuit 200 can charge or discharge the parasitic elements (e.g., resistance, inductance and/or capacitance) with the larger current I13 and I14, which can increase the response time of the output (e.g., the voltage Vout 3) of the data receiving circuit 200. In other words, the rising time (or falling time) of the voltage Vout 3 can be reduced. Which can increase the tolerance and the operation speed of the data receiving circuit 200.

Although the present disclosure and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the disclosure as defined by the appended claims. For example, many of the processes discussed above can be implemented in different methodologies and replaced by other processes, or a combination thereof.

Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, and composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the present disclosure, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed, that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present disclosure. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps. 

1-18. (canceled)
 19. A data receiving circuit, comprising: a current source, an input circuit, and a latch circuit; wherein the current source comprises: a first current source transistor having a source to receive a supply voltage, a gate configured to receive a first signal and a drain connected to the latch circuit; and a second current source transistor having a source to receive the supply voltage, a gate configured to receive the first signal and a drain connected to the latch circuit, wherein the first current source transistor and the second current source transistor are configured to provide a current to the latch circuit in response to the first signal; wherein the input circuit comprises: a first input circuit transistor having a gate configured to receive an input signal, wherein when the first input circuit transistor receives the input signal, the first current source transistor and the second current source transistor are turned on by the first signal; a second input circuit transistor having a gate configured to receive a reference signal; and a third input circuit transistor having a gate connected to receive a second signal and a drain connected to a source of the first input circuit transistor and a source of the second input circuit transistor, wherein the first input circuit transistor and the second input circuit transistor are connected with each other in a parallel manner and are connected to the third input circuit transistor in a series manner; wherein the latch circuit is configured to output an output signal in response to the input signal, wherein the output signal having a high logical value is outputted when a voltage of the input signal is larger than a voltage of the reference signal and the output signal having a low logical value is outputted when the voltage of the input signal is lower than the voltage of the reference signal.
 20. The data receiving circuit of claim 19, wherein the latch circuit comprises: a first latch circuit transistor having a source connected to the drain of the first current source transistor; a second latch circuit transistor having a drain connected to a drain of the first latch circuit transistor and a gate connected to the gate of the first latch circuit transistor, wherein the first latch circuit transistor and the second latch circuit transistor are connected in a series manner to form a first inverter of the latch circuit, wherein the drain of the first latch circuit and the drain of the second latch circuit are configured to output the output signal; a third latch circuit transistor having a source connected to the drain of the second current source transistor; and a fourth latch circuit transistor having a drain connected to a drain of the third latch circuit transistor and a gate connected to a gate of the third latch circuit transistor, wherein the third latch circuit transistor and the fourth latch circuit transistor are connected in a series manner to form a second inverter of the latch circuit.
 21. The data receiving circuit of claim 20, wherein a drain of the second input circuit transistor is connected to a drain of the first latch circuit transistor, the drain of the second latch circuit transistor, a gate of the third latch circuit transistor, and the gate of the first latch circuit transistor.
 22. The data receiving circuit of claim 21, wherein a drain of the first input circuit transistor is connected to a drain of a third latch circuit transistor, a drain of the fourth latch circuit transistor, a gate of the first latch circuit transistor, and the gate of the second latch circuit transistor, wherein a period of the second signal is about one-third of a period of the first signal.
 23. The data receiving circuit of claim 22, wherein the first and third latch circuit transistors and are PMOS transistors and the second and fourth latch circuit transistors and are N-type metal-oxide-semiconductor (NMOS) transistors.
 24. The data receiving circuit of claim 19, further comprising an equalizer connected to a drain of the second input circuit transistor, wherein the equalizer comprises: a first equalizer transistor having a source connected to ground and a drain connected to the drain of the first current source transistor; a second equalizer transistor having a source connected to ground and a drain connected to the drain of the second current source transistor; and an equalizer transistor set having a gate connected to a gate of the first equalizer transistor and a gate of the second equalizer transistor, a source connected to ground, and a drain connected to a drain of the first input circuit transistor.
 25. The data receiving circuit of claim 23, further comprising an equalizer connected to a drain of the second input circuit transistor, wherein the equalizer comprises: a first equalizer transistor having a source connected to ground and a drain connected to the drain of the first current source transistor; a second equalizer transistor having a source connected to ground and a drain connected to the drain of the second current source transistor; and an equalizer transistor set having a gate connected to a gate of the first equalizer transistor and a gate of the second equalizer transistor, a source connected to ground, and a drain connected to a drain of the first input circuit transistor.
 26. The data receiving circuit of claim 25, wherein the equalizer transistor set comprises at least three equalizing transistors being connected in a series manner, wherein the equalizer transistor set, the first equalizer transistor, and the second equalizer transistor are NMOS transistors.
 27. The data receiving circuit of claim 19, further comprising a pulse generator configured to receive the first signal and to generate the second signal, wherein after the input signal is inputted to the first input circuit transistor and before the latch circuit completes its data operation, the pulse generator is configured to generate the second signal to selectively turn off the third input circuit transistor so as to prevent the data receiving circuit from be damaged due to a short circuit the supply voltage and ground, wherein the pulse generator comprises: an inverter having an input to receive the first signal; a delay circuit having an input to receive the first signal; and a NAND gate having a first input connected to an output of the inverter, a second input connected to an input of the delay circuit, and an output configured to generate the second signal.
 28. The data receiving circuit of claim 26, further comprising a pulse generator configured to receive the first signal and to generate the second signal, wherein after the input signal is inputted to the first input circuit transistor and before the latch circuit completes its data operation, the pulse generator is configured to generate the second signal to selectively turn off the third input circuit transistor so as to prevent the data receiving circuit from be damaged due to a short circuit between the supply voltage and ground, wherein the pulse generator comprises: an inverter having an input to receive the first signal; a delay circuit having an input to receive the first signal; and a NAND gate having a first input connected to an output of the inverter, a second input connected to an input of the delay circuit, and an output configured to generate the second signal.
 29. The data receiving circuit of claim 28, wherein the input of the inverter and the input of the delay circuit are connected in parallel with each other and are connected to the gate of the first current source transistor and the gate of the second current source transistor.
 30. The data receiving circuit of claim 29, wherein the output of the NAND gate is connected to the gate of the third input circuit transistor.
 31. The data receiving circuit of claim 19, wherein the first input circuit transistor is disconnected with the first current source transistor and the second current source transistor.
 32. The data receiving circuit of claim 30, wherein the first input circuit transistor is disconnected with the first current source transistor and the second current source transistor.
 33. The data receiving circuit of claim 19, wherein the first and second current source transistors are PMOS transistors.
 34. The data receiving circuit of claim 32, wherein the first and second current source transistors are PMOS transistors. 